Call transmitter



Feb. 21,- 1939. R. F. MALLINA CALL TRANSMITTER Filed June 12; 1937 7 Sheets-Sheet 1 FIG! INVENTOR By REMALL/NA la -xmnfl ATTO NEY Feb. 21, 1939. I RY F. MALLINA 2,147,710

" CALL TRANSMITTER -Filed June' 12, 1937 7 Sheets-Sheet 2 INVE/WUR RJ-T MALL/NA ATTORNEY -Feb.2.1,1939. RFMALLINA 2,147,710

CALL TRANSMITTER Filed June 12, 1937 7 Sheets-Sheet 5 FIG. .4

INVEWTOR By RJ-TMALL/NA v flak *A'TTORNEY Feb. 21, 1939.

R. F. MALLINA 2,147,710

CALL TRANSMITTER Fi led June 12, 1937 7 Sheets-Sheet 4 FIG. 4A

II VVENTOR Rf. MALL/NA 9. w aa AFTORA/EY 21 1939 I R. k. MALLiNA 1 2,147,710

- GALLTRANSMITTER Filed June 12, 1937 7 SheetsSheet 5 lNl EN TOR R. f. MALL/NA A TTORNE Y Feb. 21, 1939. R. F. MALLINA CALL TRANSMITTER Filed June 12, 1937 "r Sheets-Sheet '6 FIG. /4

EF GHI JKL VWXY z S 2 R P INVEN TOR REMALL/NA Arronmy v Patented Feb. 1939 CALL TRAN SMITTER' Rudolph F. Mallina, New York, N. Y.,'asslg'nor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 12, 1937, Serial No. 147,911

3 Claims. .(01. 179-410 This invention relates to call transmitters-oi the type used in automatic telephone systems for controlling the operation of switches for. establishing talking connections.

The object; of the invention is to provide a call transmitter oi the type above referred to which will be simple to operate, positive in operation, and which will effect a material reduction in the time for transmitting any given telephone call designation, as compared to call transmitters now in use. a

According to the'invention, a set of manually operable key members numbered to represent digits is provided for operating either singly or in combination a number of vibrating reeds in the coil of an electromagnetic device connected to the telephone line. These reeds form part of the electromagnetic device and are tuned to different frequencies for generating alternating currents of these frequencies in the telephone line to which the coil is connected and thereby energizing electrical filter devices placed at the exchange for selectively operating electromagnets which in turn control the operation of associated switches for establishing telephone connections correspondingto the digit key members which have been operated. More specifically, a mounting plate orbase is provided for securing supporting means for a shaft used for pivotally mounting a plurality of lever members disposed for operation either singly or in combination by the manual operation of a set of digit keys. Means carried by the lever members is provided for vibrating the reeds in the coil oi an electromagnetic device and adjacent the pole-pieces of a permanent magnet for generating alternating current signals in the telephone line, there being ten signals effected by the operation of such reeds. Means is provided for yieldably holding, the lever members in ,operative relation with their associated digit keys,

which are held in the non-operated or normal position by spring means abutting against a guiding plate for the keys and the undersides of the key buttons. Adjustable means is provided for controlling the amplitudes of the vibrating reeds as to generate the required voltage value of the signals in the telephone line for operating selective magnets through electrical filter devices at 'the telephone exchanga the operation of such magnets being dependent upon the tune frequencies of the reeds, while means in the base plate is provided for receiving a casing for housing the operating mechanism of the transmitter and to serve as a cradle for a telephone handset.

Fig. 13 is a side view thereof showing Other features and advantages of the inventionwill' appear from the following description and by the claims appended thereto, reference being had to the accompanying drawings in which- Fig. l is a top assembly view; Fig. 2 is a side view thereof shown with portions of the casing cut away; Fig. 3 is a front view shown with portions of the casing cut away;

Fig. 4 is a top assembly view shown with the 1 casing removed from the base and with a number of operating parts in section; I

Fig. 4A is a top view of a mechanism used for preventing the operation of two digit-keys simultaneously;

Fig. 5 is a longitudinal sectional view taken on line 5-5 of Fig. i;

Figs. 6 and 6A are detail views;

Fig. 7 is a rear view showing the lever members pivoted on their supporting shaft, this shaft 2 being shown with portions cut away and the sup--. porting'plate in. section taken on line'l-I of Fig.

Figs.'8, 9 and 10 are detail views showing one of the reeds actuating mechanism in a number of difierent positions;

Fig. 11 is a partial view of the lever members showing the plunger portion of the keys in section taken on line H-il of Fig. 3;

Fig. 12 is a perspective view of a modification of the calltransmitter;

the casing with portions cut away;

' Fig. 14 is a top assembly view shown with the casing removed;

Fig. 15 is a perspective view of the digit key assembly;

Fig. 16 is a partial top view of the reeds actuating mechanism showing a number of operating parts in section;

Fig. 17 is a partial view of a'modiiication of the mechanism for preventing the operation of two digit keys simultaneously; and r 4 Fig. 18 is a partial side view showing one of the key members in the operated position.

In the call transmitter of the invention, as shown in Figs. 1, 2, 3 and 4, the base plate 20 cooperates with the casing 2! to form a housing for the call transmitter mechanism and a cradle for the telephone handset TH, shown in Fig. 12, the

casing 2i being secured to the base 20 by a plurality of screws passing through clearance holes CH'inthe plate 20 shown in Fig. it for engaging screw-threaded holes ST in the casing portion 2| as shown in Fig. 1.

rial, for clamping the coil 56 on the front faces 0n the -base plate 24 is mounted ordinary switchhook springs (not shown) for operation by plungers 23 shown in Figs.- 1, 2 and 3, upon the placing of the handset TH in the cradle portion of the casing 2|, and a ringer device 24, shown in Figs. 2, 13 and 14, is mounted on a supporting i'rame 25 in turn secured to the plate 20 by a number of screws SC.

On plate 23, in position adjacent the ringer supporting frame 25 is securely mounted a crossbar 23 having its two ends bent at right angles for supporting a shaft 26 and on this shaft is pivotally mounted a set of lever members LI, L2, L3, L4, shown in Figs. 2, 4, 5 and 7., These levers are held in normal unoperated position against the edge of a cross-bar 28 by respective ribbon springs, such as 21, having one of their ends clamped between the base plate 23 and the crossbar 29, this cross-bar being secured to the plate 20 by a number of screws 30.

The end portions of cross-bar 23 are provided with bearing portions BP for pivotally mounting the arms. 3| and 32 of .a bar 33 normally held in operative relation with the lever members LI, L2, L3 and L4, through a lug 34 carried by arm 3| of this bar and resting on a stud 36 of insulating material carried by a switching spring 35, so that the operation of any one of lever members LI, L2, L3 and L4 is effective to operate the switch spring 35 for opening the contact between this spring and spring the switch spring 33 through the engagement of stud 36 with this switch spring for disengaging it from switch spring 33, and thereby closing the contact between the switch spring "and switch spring 46 provided for short circuiting the telephone receiver during the transmitting of the call designation.

The switch springs 31, 35, 38, 39 and 40 are mounted in a pile-up arrangement on the plate 26 and are securely held in adjusted position thereon by screws 4| and 42.

On the base plate 20 is mounted an inverted U-shaped support straddling the lever members L2 and L3, as shown in Figs. 4 and 5. This support is held securely on the base plate 20 by screws 43 and '44 and on this support are mounted in superposed relation ,to each other, the rectangularly-shaped permanent magnets PM I and PM2 between which the vibrating reeds RI, R2, R3 and R4, shown in Fig. 6, and the plates 46 and 41 are clamped by screws 808 while the magnets and reed assembly thus formed is held on the support 46 by screws SCA and SCB, the plates 46 and 41 having their front edges formed'diagonally to clamp diflerent lengths of the reeds in order to obtain dinerent vibrating rates.

Reeds RI, R2, R3 and R4 extend through an oblong-shaped opening of a coil 53 for movement adjacent the pole-pieces 6| and 52 which serve, in cooperation with the screws 63 and spacer members 63 and 6| ofmagnetic mateof magnets PMI and PM2, as shown in Figs. 2, 4 and 5, the ends'of the coil wire, W, WI being secured to a terminal bank 63 secured to the plate 26 by a screw 33.

The free ends of reeds RI, R2, R3 and R4 are disposed in enga eable relation with respective trigger members TI, T2, T3 and T4 pivoted at the ends oi upwardly ex ending lug portions 62, 63, 64 and 65 formed and L4, respectively. Triggers TI, T2,-T3 and T4 are each'provided with a projection as PI,

top end of guiding plunger portion of the keys.

31 and operating with levers LI, L2, L3

keys KI-, K2, etc.,

which, in cooperation with an adjustable screw 61, controls the disengagement of the trigger members TI, T2, T3 and T4 with their respective reeds RI, R2, R3 and R4 upon the downward movement of levers LI, L2, L3, and L4 as effected by the operation of the key members KI, K2, K3, K4, K5, K6, K1, K3, K9 and KID as shown in Figs. 1, 2 and 3. Each of the trigger members TI, T2, T3 and T4 is provided with projecting lug portions MP' which engage the under side of their associated vibrating reeds RI, R2, R3 and R4 for preventing the continued vibrations of these reeds when their actuating keys and associated lever members are returned to normal non-operated position, as shown in Figs. 2, 3 and 5, such engagement being eifected upon the engagement of the projections PI of the triggers TI, T2,- T3 and T4 with stops afforded at the slots in a plate 66 which also serves as support for the adjustable screw 61.

Each key KI, K2, K3, etc. consists of a cylindrically-shaped button secured at the end of a plunger of rectangular cross-section. These keys are guided in their downward and upward movements by a plate 1I engaging. the cylindricallyshaped buttons and a plate 10 engaging the The plate H is held in spacedand oblique relation with respect to plate 10 by a plurality of spacer members 14 shown in Figs. 2, 4 and 5, while the plate 10 is formed integrally with two upright flanges 84 and 65 having portions 36 and 81 for securing the key assembly thus formed on the base plate 20, as by a number of screws 80, 8|, 82 and 83, the key members KI, K2, K3, etc., being held in .the non-operated position by compression springs 15 shown in Figs. 2, 3 and 5, having one of their ends abutting against the under side of the key buttons and their other ends abutting on the top disposed surface of guiding plate 10.

The lower end portions of the digit keys are disposed in engageable relation with' the lever members LI, L2, L3 and L4, for actuating them and the trigger members TI, T2, T3 and T4 carried thereby independently or'in combination for actuating the vibrating reeds RI, R2, R3 and R4 As shown in Fig. 4, keys KI, K2, K3 and K4 qp ratively engage the lever members LI, L2, L3 and L4 respectively for independently actuating the reeds RI, R2, R3 and R4, the key K5 operatively engages the lever members LI and L2 for simultaneously vibrating the reeds RI and R2,

the key K6 operatively engages the-lever memmembers L2 and L4 for simultaneously vibrating T the reeds R2 tively engages simultaneously vibrating the reeds RI and R4.

Although good results have been obtained with reeds R4, R3, R2'and RI, respectively, tuned to vibrate at frequencies of 400, 500, 625 and 780 and R4, and the key KIIi operacycles, other rates of frequencies, especially in the higher ranges, may be used with equally good results.

A mechanism is provided for preventing the accidental operation of more than one of the simultaneously. In this mechthe lever members LI and L4 foranism, as shown in Figs. 3, 4, 4A and 5, the plunger portions of keys Kl, K2, K3, K4, K5, K6, Kl, K8, K9 and KIO are each formed with a perpendicularly extending lug portion Yl, Y2, Y3, Y6, Y5, Y6, Y1, Y8, Y9, and Ylll, respectively, provided. for individually engaging a row of balls RB in a track 90 secured on the base plate 20 as by screws 9|. The track 90 is provided with stops 92 and 93., best seen in Fig. 4A, limiting the length or the track to a distance equal to the sum of the diameter of the balls RB plus a clearance equal to the thickness of one of the lugs Yl, Y2, Y3, etc., between two of the balls RB, as when one of these keys is operated the balls are moved in the race-track in position against each other and against the stops 9t and 93 at the ends of'the track for preventing the operation of another key. until the previously operated key is released by the operator for permitting it to return to normal unoperated position under the'tension of its retractile spring it.

In a typical example of operation, supposing that a telephone call designation such as AB5-- 6789 is to be transmitted. The key Kt having the character ABC-2 printed thereon is op'erated against the resistance of its retractile spring iii The operation of this key is effective to actuate the lever L2 against the resistance of its own retractile spring ll shown in Figs. 2, 5 and '7, and thereby moving the trigger member T2 irorntheposition shown in dotted. lines in Fig. 8 to the position shown in Fig. 9 for flexing the reed Rt to a point wherein the lug Pit of this trigger engages the end of its associated screw t'll to cause the pivotal movement of the trigger Ti for releasing the reed which, due to its resiliency, vibrates at its tuned frequency, that is,'625 cycles in the coil 5ll and between the pole-pieces ti and M for generating alternating current of that frequency in the coil and thereby in the telephone line connected thereto. The second operation of key member Ki for signaling the digit B, the operation of. reed R'l, is, ofcourse, effected in a manner similar to that for signaling the letter A. Upon the release and the subsequent return movement of key Kt and lever L2 to normal position, the trigger T2 is caused to pivot to its normal position due to the lug Pi engaging the abutment afforded at the end of its guiding slot in theplate 55 for reengaging its.

associated reed R2, as shown in Fig. 10. In that position, however, it is to be noted that the portion MP of the trigger T2 engages the under side of the reed Rt as to prevent the continued vibration of this reed while a succeeding key is being operated. i I

in the operation of key K5 for signaling the digit 5, the operation of this key is eiiective to actuate the levers Ll and Lt for simultaneously vibrating the reeds Rl tuned ata frequency of 780 cycles, and reed R2, tuned at a frequency of 625 cycles, thereby difierentiating from the signal effected by the operation of key Kt.

The operation of key K6 for signaling the digit 6 is effective to actuate the levers-L2 and L3 simultaneously and thereby the reeds R2 tuned at a frequency of 625 cycles and reed R3 at a he quency of 500 cycles.

The operation of key K1 is effective toactuate the levers L3 and L4 for simultaneously actuating the reeds R3 tuned as above mentioned to a ireduency of 500 cycles, and-the reed R4 tuned at a frequency of 400 cycles.

The operation of key K8 is effective to actuate the levers LI and L3 for simultaneously actuating the reeds RI timed at a frequency of 780 cycles, and reed R3 tuned at a frequency of 500 cycles.

The operation "of key K9 is effective to simultaneously actuate the levers L2 and Ll for actuating the reeds R2 tuned at a frequency of 625 cycles and the reed RA tuned at a. frequency .0! 400 cycles, while the operation of key KID is effective to simultaneously actuate the levers Li and Lil for vibrating'reeds Ri tunedat a frequency of 780 cycles, and R 3 tuned at a. frequency of iOO cycles, thus differentiating in ten combinations the signals transmitted by the operation of the ten digit keys Kl, Ki, K3, etc.

. In .a modification of the reed operating mechanism as shown in Fig. 11, five levers Ll, L2, L3,.

is and L5 are operated by the ten digit keys Kl, K2,, K3, Kt and K5 for actuating five vibrating reeds shown in Fig. 6A through the operation of a corresponding number of trigger members in the manner described in connection with reeds Rl, R2, R3 and RM of Figs. d and 6. In this modiflcation, however, the reed R5 is tuned to vibrate at a frequency of 975 cycles and the'levers Ll L2, Li Li and Lt, and thereby their associated vibrating reeds, are operated in ten combinations of two reeds upon the operation of the key members Kl, Kt, Kill and Kt, etc. According to this mechanism, as shown in Fig. ll, key Kl operates levers Ll and Lt and thereby reeds R5 and El; key K2 operates levers Li and Li and thereby the reeds El and R2; key K3 operates levers Lt and L l and thereby the reeds R2 and Rt; key K l operates levers L l and Lli and thereby reeds Rd and E i; key Kb operates levers Li and L3 and thereby the reeds R'dand Ril; key Kt operates levers L2 and Lt and thereby reeds Pat and Rd; key Kl operates levers Lt and L5 and thereby reeds R2 and E i; key Kt operates levers Li and L l and thereby reeds R5 and R3; key Kd operates levers Li and L5 and thereby reeds Bi and E i; and key Kill operates levers Li and L5 and' thereby reeds R5 and R ll;

The principal advantage in the use of five reeds in combination of two lies in the fact that provision at the exchange is easily made for routing all signals in which one of the reeds fails to operate to an operator instead of making a wrong telephone connection. 4

In another modification of the reed operating mechanism shown in. Figs. 12, 13, i i, 15, 16, 1'7 and 18; the shaft it pivotally supports a plurality of U-shaped yokes llll, ltd, llllt, ill and ltli, the arms ltd and it'll oia cross-bar ltd and the lever portions ofkeys Kl, K2, Kt, K l, K5, Kt,-Kl, K8, K9 and Kit. The lever portions of keys Kl, Ki,

dil

ill? etc. extend is superposed relation with respect to the U-shaped yokes ml, ltd, ltd, etc., and each TdY, TM! and T5Y, in engageable relation with.

the vibrating reeds Rlil', REY, R3Y, R432, and R5Y tuned as stated in connection with the reeds shown inFig. 6A for vibrating at the frequencies of. 9'75 cycles, 780 cycles, 625 cycles, 500 cycles and 400 cycles, respectively, upon the operation of the keys Kll, K12, Ki3, etc., in a manner that will be hereinafter described in detail.

The lever portions of keys Kl K2, K3, etc., are provided with downwardly projecting lugs shown in Figs. 13, 15, 18 and in section in Fig. 16 disposed in operative relation with the U-shaped yokes llll, I02, I03, I04 and I05 for operating them in pairs. Key Ki, as shown in Fig. 16, is

lid

provided with lugs I I and III engaging the yokes IM and I 02 for actuating the trigger members TYI and TY2 for operating the reeds RIY and RZY. Key K2 is provided with lugs H2 and H3 for actuating the yokes IN and I04 for operating the trigger members TYI and TY4 for operating the reeds RIY and R4Y. Key K3 is provided with lugs H4 and H5 i'or actuating the yokes I02 and I03 for operating the trigger members TY2 and TY3 for operating the reeds R2Y and R3Y. Key K4 is provided with lugs I I8 and IIHor actuating the yokes I02 and I05 for actuating the trigger members TYZ' and TY5 for operating' the reeds RH and R5Y. Key K5 is provided with lugs H8 and I for actuating the yokes I03 and I05 and thereby the trigger members TY3 and TY5 for operating the reeds R33? and MY. Key K5 is provided with lugs I2I and I22 for actuating the yokes I M and I03 for operating the trigger members TYI and TY3 i'or actuating the reeds RIY and R3Y. Key K1 is provided with lugs I23 and I24 for actuating the I yokes MI and I05 and thereby the trigger members TYI and TY5 for actuating the reeds RIY and 1251. Key K8 is provided with lugs I25 and I28 for actuating the yokes I04 and I02 and thereby the trigger members TYI and m for actuating the reeds R2Y and R4Y. Key K0 is provided with lugs I 21 and I28 for actuating the yokes I03 and I04 and thereby the trigger members TY3 and TY4 for actuating the reeds R31! and RAY. Key KIO is provided with lugs I29 and I30 for actuating the yokes I04 and I05 and thereby the trigger members TY4 and 'I'YS for actuating the reeds R4Y and 1353!, thus differentiating the operation of the keys KI, K2, K3, etc., into ten combinations of two frequencies each.

The lever portions of key members KI, K2, K3, etc. are each provided at their free ends with downwardly extending lugs XI, X2, X3, X4, X5, X6, X1, X8, X9 and XIII. shown in Figs. 13, 15, 16, 17 and 18, each' movable in a respective slot in a guiding plate I40 for individually engaging a row of balls RB in a track I H formed at the lower end portion of guiding plate I40 as shown in Fig. 13, this plate being secured at both ends to the base plate 20 by screws I42 and I43.

The track I is provided with stop elements I44 and I45 limiting the length of the track distance equal to the sum of the diameter of balls RB plus a clearance equal to the thickness of one of the lugs XI, X2, X3, etc.. so that upon the engagement of one of these lugs between two of the balls as when one of the keys is operated, the balls are moved in the race-track in position close to each other for preventing the-operation of another key until the previously operated key is returned to normal unoperated position. In this modification. the return movement of each key member KI, K2, K3. etc.. is ifected through the return movement of the U-shaped yokes IOI, I02, I03, I04 and I05, by the tension of the helical springs I4'I shown in Figs. 13, 14, 15, 16 and 18, hooked at one of their ends to downwardly extending pair of arms I48 formed with the U-shaped yokes IOI, I02. I03, etc.', adjacent their bearing portions while the other ends 01' these springs are hooked to the upright pivoted arms I08 and extending portions of two right-angled strip I45 and I50 secured to the base plate 20 b; screws XYI shown in Figs. 14, 15 and 16.

Similarly the bar I08 which is formed with th' I01 is held in engage! side of the lever per etc., by two retractili relation with the under tions of keys KI, K2, K3,

springs I5I and I52 having similar ends hookec to downwardly extending lugs formed with th( arms I05 and I0! of this bar and their othe1 ends to the angle pieces I48 and I50, respectively.

The movement of bar I08 upon .theoperation of anyone of the keys is effective to operate the switch springs 35, 35, 31, 38, 30 and 40 in the manner described in connection with the call transmitter shown in Figs. land 2.

What is claimed is:

1. In a call transmitter, a base. a shaft, means carried by said base for supporting said shaft, a plurality of digit key members and U-shaped yokes pivoted on said shaft, said yokes being disposed for operation in pairs by the movement of said key members, a plurality of reeds, a trigger member carried by each, of said yokes disposed in engageable relation with the corresponding one of said reeds and means for translating the operation of said reeds for transmitting telephone call designations corresponding to the operation of said digit key members.

2. In a call transmitter, a base, a bracket carried by said base, a shaft supported by said bracket, a set of key members pivotally mounted: on said shaft, a plurality of U-shaped yokes having parallel arms pivoted on said shaft on each side of said set of'key members with the cross-bar portions ofsaid yokes disposed for operation in pair combinations by the operation of each of said key members, a projection carried by each of said levers, a pawl pivoted on each of said projections, a reed vibrated by the operation of each of said pawls upon the operation of said key members in said combinations,

a stop element carried by said base for disengaging said pawls'from said reeds upon a pre-.

phone call designations.

3. In a call transmitter, a base, a set of pivoted digit key members, a set of pivoted U-shaped yokes having their cross-bar portions disposed in engageable relation with said key members, a common supporting shaft for said yokes and said key members, a permanent magnet formed of two parts, metallic plates disposed between said parts and reeds adjusted to diiferent frequencies clamped between said plates, trigger members carried by said yokes for vibrating said reeds upon the operation of said key members, and a device responsive to the operation of said reeds for transmitting telephone call designations corresponding to the operation of said digit key members.

RUDOLPH F. MALLLNA.

- translating the operation of said reeds into tele- 

